This invention, which relates to boats of any types, will raise and lower a boat out of the water for mooring thereby protecting the hull from the harmful effects of the water.
1. Background
Owning a boat can require a high level of maintenance. To reduce the amount of time spent storing, transporting, and launching their boat, many owners choose to moor their boat. However, leaving a boat in the water will cause a build-up of growth and residue on the hull. This growth can cause permanent staining of the hull and even blistering of a fiberglass hull. At the very least, this growth and residue will require a significant amount of cleaning.
There are currently several devices on the market that address this problem by lifting the boat above the water level. Although there are many designs, they are basically large mechanical structures with several inherent drawbacks. Besides being quite expensive, these structures are usually too bulky and difficult for the user to transport and install himself. In many cases, the mooring slips provided by marinas are not wide enough to accommodate these devices. Also, some of these structures are supported by feet that rest on the bottom of the lake or river. These feet require a firm bottom with minimum and maximum depth limitations. The feet usually support a rack device that in turn supports a movable platform that supports the boat hull. The rack device is usually raised by a winch system either manually or by an electric motor. Once installed, these systems often need adjustment for changing water levels. It is not uncommon for a boat to become stuck on the lift because the water has dropped to a level lower than the lowest point of travel of the platform. It is also not uncommon for the feet of these devices to sink too far into the bottom and cause tilting of the device.
There is also a system on the market that uses large pontoons to support a platform. These pontoons sink as water fills them and raise again as the water is forced out and replaced with air. This system has no maximum water depth limitation and adjusts automatically for changing water levels. However, it does have a minimum water depth limitation and is much more expensive than previously mentioned systems. This type of lift also requires significant structural support from and mechanical connections to the dock itself. Many marinas do not allow these connections. This type also requires 110 volt AC electrical power which is often not available at the dock.
Another drawback of these mechanical systems is that they can cause significant damage to the hull or propeller if the boat is misguided onto the lifting device. And, they do not allow the boat to be lifted at an angle to facilitate draining of the hull through the transom drain. Also, because of their size, they are often stored near the water in a very unsightly manner in a users' yard. There are other types of boat lifting systems that are basically overhead hoists. These systems do not have water depth limitations but are also quite expensive and also require a significant overhead structure and dock structure and are very difficult to install or relocate.
2. Prior Art
Devices for lifting boats are among some of the oldest found in the patent art. U.S. Pat. No. 515,878 to Haley and Foster, March 1894 teaches a multiplicity of inflatable bags covered with a heavy netting of cord or rope, joined together by chains. U.S. Pat. No. 4,075,965, to Lasch, February 1978 teaches inflatable cylindrical bodies positioned beneath a boat and secured in place with straps. These are for the purpose of lifting the boat high enough to drain water from the boat through the transom drain opening. U.S. Pat. No. 5,341,756 to Hinze, August 1994 teaches an apparatus with flexible, inflatable toroidal shaped floatation devices with bands for securing them relative to the watercraft. U.S. Pat. No. 3,570,256, to Thompson, March 1971 teaches an inflatable birth for covering the water-submerged portion of a boat to entrain water against the hull for stagnation of the entrained water.
The above mentioned inventions teach some of the elements of this invention but they do not teach all of the elements nor the combinations. Specifically, none of these teach a device that will keep itself floating in position ready to accept the boat. Nor do any of these teach a device that guides the boat into the proper position on the device; nor do they teach a device that does not require strapping or mechanically fastening the lifting device to the boat. Thompson teaches a device suspended vertically by securing it to a boat slip but does not teach a lifting device.